Torchlight 2 Walkthrough Part 18: The Cave In
This mission takes place smack dab in the middle of Some Assembly Required. Before you can proceed with that quest, you will have to tackle this one. This mission requires that you travel to the Abandoned Sawmill area, which can be a dangerous trip on its own. Watch out for the numerous enemies that will no doubt be hounding you on your trip. When you begin to near the Abandoned Sawmill, you will find that the area has been dominated by wolf type enemies, including both Wolves and Werewolves. Both of these enemy types can move very fast and hit very fast. Your first order of business when cornered by groups of these enemies should be to cast slowing or stunning spells against them so that they aren't so fleet of foot when you go in for the kill. If you get surrounded, you're as good as dead unless you can escape quickly. Try to tackle them in small groups, instead.
Make your way into and through the Abandoned Sawmill. Follow your waypoint marker on your map, and be sure to search every nook and cranny for extra treasures and the like. You know the drill. You will soon stumble upon a boss monster, the Grizzled Alpha. This massive wolf creature won't be as tough a fight as he might initially appear. Instead, he is actually a pretty straightforward fight. He will naturally summon a few minions to his side. Take care of them first. When you are ready to tackle the Grizzled Alpha himself, pour on the slowing and stunning effect, or deal Poison damage or some other continual damage effect. This way, even if you can't catch up to the speedy wolf you can still damage him somehow.
When the boss is defeated, head back to the Blightbogs and speak with the soldier to blow open the pass. Now you can proceed to the next phase of the Some Assembly Required mission.